Thanks for all the suggestions! I'll start a list on the sidebar so you can check for your favorites.
Meanwhile, here are some of mine. Now, I can't take all the credit for all of these -- this was a collaborative effort with Franki and Karen T. over breakfast, and with owner Sally at Cover to Cover (children's bookstore extraordinaire) later.
Mrs. Kempczinski in GOOD LUCK, MRS. K by Louise Borden. The whole book is a love letter to a beloved teacher who misses the last months of school because she has cancer. But she comes back!
Dumbledore in the HARRY POTTER books.
Ms. Clayton in SCHOOL STORY by Andrew Clements. He has lots of good teachers. Thank you, Mr. Clements! This one is the teacher who helps the girl get her book published.
I also liked Mr. Maxwell in Clements' A WEEK IN THE WOODS. We take our kids to camp, so I could appreciate his organization in preparation for the trip. He made some mistakes and bad assumptions, but he (along with the main kid character) changed and grew.
Mr. Faulker, in THANK YOU, MR. FAULKER by Patricia Polacco. That's just obvious.
Ms. Isabel Hussey in CHASING VERMEER and THE WRIGHT THREE by Blue Balliett. She is energetic and child-centered. Her teaching is rigorous and the work her students do is authentic. She follows the students' agendas and her own, and their studies go further and deeper than any curriculum developer or textbook writer could ever imagine. She's a light in the darkness of standards-based teaching.
Miss Stretchberry in LOVE THAT DOG by Sharon Creech. You have to draw a lot of conclusions about Miss Stretchberry from Jack's poetry journal, but who wouldn't love to have a teacher who is so passionate about poetry, and so gently persistent in growing her writers?
Mr. Birkway in WALK TWO MOONS by Sharon Creech. Boy does he screw up reading the kids' journals aloud, but he realizes it and back pedals. I can kind of relate to that sort of thing happening now and then...
Mr. Todd, JUDY MOODY's teacher. He'd have to be a saint to put up with Judy!
Mr. Slinger, LILLY'S (PURPLE PLASTIC PURSE, by Kevin Henkes) teacher. I love him right down to his cheese puffs and Birkenstock sandals!